[CRIU] [PATCH RFC 23/30] inet: Use task_st futex for notification instead of per-port

[Kirill Tkhai]

On 08.11.2016 16:08, Pavel Emelyanov wrote:
> Why doesn't per-socket notification work?

It works, but the idea is to use task_st for waiting of every events.

> On 11/01/2016 05:34 PM, Kirill Tkhai wrote:
>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>> ---
>>  criu/sk-inet.c |   26 ++++++++++++++++++++------
>>  1 file changed, 20 insertions(+), 6 deletions(-)
>>
>> diff --git a/criu/sk-inet.c b/criu/sk-inet.c
>> index 6a0a2d2..8832c91 100644
>> --- a/criu/sk-inet.c
>> +++ b/criu/sk-inet.c
>> @@ -33,7 +33,7 @@ struct inet_port {
>>  	int port;
>>  	int type;
>>  	struct list_head type_list;
>> -	futex_t users;
>> +	atomic_t users;
>>  	mutex_t reuseaddr_lock;
>>  	struct list_head list;
>>  };
>> @@ -45,7 +45,7 @@ static struct inet_port *port_add(struct inet_sk_info *ii, int port)
>>  
>>  	list_for_each_entry(e, &inet_ports, list)
>>  		if (e->type == type && e->port == port) {
>> -			futex_inc(&e->users);
>> +			atomic_inc(&e->users);
>>  			goto out_link;
>>  		}
>>  
>> @@ -57,8 +57,7 @@ static struct inet_port *port_add(struct inet_sk_info *ii, int port)
>>  
>>  	e->port = port;
>>  	e->type = type;
>> -	futex_init(&e->users);
>> -	futex_inc(&e->users);
>> +	atomic_set(&e->users, 1);
>>  	mutex_init(&e->reuseaddr_lock);
>>  	INIT_LIST_HEAD(&e->type_list);
>>  
>> @@ -514,6 +513,19 @@ static int inet_validate_address(InetSkEntry *ie)
>>  	return -1;
>>  }
>>  
>> +static void dec_users_and_wake(struct inet_port *port)
>> +{
>> +	struct fdinfo_list_entry *fle;
>> +	struct inet_sk_info *ii;
>> +
>> +	if (atomic_dec_return(&port->users))
>> +		return;
>> +	list_for_each_entry(ii, &port->type_list, port_list) {
>> +		fle = file_master(&ii->d);
>> +		set_fds_event(fle->pid);
>> +	}
>> +}
>> +
>>  static int post_open_inet_sk(struct file_desc *d, int sk)
>>  {
>>  	struct inet_sk_info *ii;
>> @@ -536,7 +548,8 @@ static int post_open_inet_sk(struct file_desc *d, int sk)
>>  	if (ii->ie->opts->reuseaddr)
>>  		return 0;
>>  
>> -	futex_wait_until(&ii->port->users, 0);
>> +	while (atomic_read(&ii->port->users))
>> +		wait_fds_event();
>>  
>>  	val = ii->ie->opts->reuseaddr;
>>  	if (restore_opt(sk, SOL_SOCKET, SO_REUSEADDR, &val))
>> @@ -554,6 +567,7 @@ int restore_ip_opts(int sk, IpOptsEntry *ioe)
>>  
>>  	return ret;
>>  }
>> +
>>  static int open_inet_sk(struct file_desc *d)
>>  {
>>  	struct inet_sk_info *ii;
>> @@ -641,7 +655,7 @@ static int open_inet_sk(struct file_desc *d)
>>  			inet_connect(sk, ii))
>>  		goto err;
>>  done:
>> -	futex_dec_and_wake(&ii->port->users);
>> +	dec_users_and_wake(ii->port);
>>  
>>  	if (rst_file_params(sk, ie->fown, ie->flags))
>>  		goto err;
>>
>> .
>>
>